Muklis Ali, Jakarta – Militant groups may be planning to disrupt Indonesian elections this year with attacks on political rallies, police said on Tuesday. Indonesia is due to hold parliamentary polls in April and its first direct presidential election in July. Campaigning will begin in March.

"In every mass gathering, there is a chance of chaos. They can infiltrate people who can use the situation," national police chief Da'i Bachtiar said when asked about preparations for the elections.

Election campaigns in Indonesia, where there are 145 million eligible voters, are often marked by rowdy and sometimes violent rallies.

Bachtiar said political parties had to work with police to avert trouble. "It will be very precarious if they use explosions. That's why all political parties and other groups should cooperate with us so that the opportunity for infiltration by terrorist groups can be tackled early," he said.

Indonesia, the world's most populous Muslim country, has suffered a series of attacks in recent years blamed on Islamic militants from the al Qaeda-linked Jemaah Islamiah group. The worst was the bombing of a nightclub on the tourist island of Bali in October 2002 that killed 202 people, most of them foreign tourists.

Indonesian authorities say Jemaah Islamiah has been fragmented after dozens of arrests and convictions of members since the Bali blasts. But police say several key JI members, including a master bomb-maker, remain at large.